Import existing project into smart template project?

I have created a web part for sharepoint in visual studio 2005 IDE by. I created a class library project and installed the dll into GAC and added the web part in my web application by adding safe controls in web.config.
Now my question is that "Is it possible to import an existing web part project created using class library project into a smart template project and create a setup file for that??? if it is possible can anybody give me proper direction of how
to proceed??